Sheet supply device and image forming apparatus

ABSTRACT

According to an embodiment, a sheet supply device includes a stacking unit, a first roller, a second roller, and a stopper. The stacking unit has a stack surface on which sheets are stacked. The first roller conveys a sheet from the stacking unit in a conveying direction. The second roller conveys the sheet conveyed by the first roller. The stopper has an abutting surface. The stopper is rotatable around a rotation shaft along a width direction. The stopper rotates such that a posture of the stopper switches between a first and a second posture. The first posture has a first angle at which an angle between the abutting surface and the stack surface is an obtuse angle. The second posture has a second angle at which an angle between the abutting surface and the stack surface is an obtuse angle, the second angle being more than the first angle.

FIELD

Embodiments described herein relate generally to a sheet supply deviceand an image forming apparatus.

BACKGROUND

In a sheet supply device of an image forming apparatus, a sheet bundlein which a plurality of sheets are stacked is stacked. The sheet supplydevice conveys the sheets of the sheet bundle one by one.

However, in the sheet bundle, the adhesion force between the sheets maybe strengthened. In this case, multiple sheet feeding is likely to occurduring sheet conveyance.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a configuration example of animage forming apparatus according to an embodiment;

FIG. 2 is a schematic plan view illustrating a sheet supply device;

FIG. 3 is a schematic configuration diagram illustrating the sheetsupply device;

FIG. 4 is a schematic configuration diagram illustrating an operation ofthe sheet supply device;

FIG. 5 is a schematic configuration diagram illustrating an operation ofthe sheet supply device;

FIG. 6 is a schematic plan view illustrating a sheet supply deviceaccording to a comparative embodiment;

FIG. 7 is a schematic configuration diagram illustrating a sheet supplydevice according to a comparative example;

FIG. 8 is a schematic configuration diagram illustrating an operation ofthe sheet supply device;

FIG. 9 is a schematic configuration diagram illustrating an operation ofthe sheet supply device;

FIG. 10 is a schematic diagram illustrating a modification example of astopper; and

FIG. 11 is a schematic diagram illustrating a modification example ofthe stopper.

DETAILED DESCRIPTION

According to an embodiment, a sheet supply device includes a sheetstacking unit, a first roller, a second roller, and a stopper. The sheetstacking unit has a stack surface on which a plurality of sheets arestacked. The first roller is configured to convey an uppermost sheetamong the sheets from the sheet stacking unit toward a downstream sidein a conveying direction of the sheet. The second roller is configuredto further convey the sheet conveyed by the first roller. The stopperhas an abutting surface against which a leading end of the sheet on thedownstream side in the conveying direction abuts. The stopper isconfigured to be rotatable around a rotation shaft along a widthdirection of the sheet parallel to the stack surface and perpendicularto the conveying direction. The stopper rotates around the rotationshaft such that a posture of the stopper switches between a firstposture and a second posture. The first posture has a first angle atwhich an angle between the abutting surface and the stack surface is anobtuse angle. The second posture has a second angle at which an anglebetween the abutting surface and the stack surface is an obtuse angle,the second angle being more than the first angle.

Hereinafter, a sheet supply device and an image forming apparatusaccording to an embodiment will be described with reference to thedrawings. In the respective drawings, the same components will berepresented by the same reference numerals. The dimension and shape ofeach of the members are illustrated in an exaggerated or simplifiedmanner.

As illustrated in FIG. 1, an image forming apparatus 100 is, forexample, a multi-function peripheral. The image forming apparatus 100includes a display 110, a control panel 120, a printer unit 130 (imageforming unit), a sheet accommodation unit 140 (sheet supply device), andan image reading unit 200. The printer unit 130 in the image formingapparatus 100 may be a device that fixes a toner image or an ink jetdevice.

The image forming apparatus 100 forms an image on a sheet with adeveloper such as toner. For example, the sheet may be a sheet-shapedrecording medium such as paper, label paper, a resin sheet, a post card,or an envelope.

The display 110 is an image display device such as a liquid crystaldisplay or an organic EL (Electro Luminescence) display. The display 110displays various information relating to the image forming apparatus100.

The control panel 120 includes a plurality of buttons. The control panel120 receives the operation of a user. In addition, the control panel 120outputs a signal corresponding to the operation input by the user to acontrol unit 150 of the image forming apparatus 100. The display 110 andthe control panel 120 may be configured to be integrated into a touchpanel.

The printer unit 130 forms an image on the sheet based on imageinformation generated by the image reading unit 200 or image informationreceived through a communication path. The printer unit 130 forms animage through, for example, the following process. The printer unit 130forms an electrostatic latent image on a photoconductive drum based onthe image information. The printer unit 130 applies the developer to theelectrostatic latent image to form a visible image.

Specific examples of the developer include toner. A transfer unit of theprinter unit 130 transfers the visible image to the sheet. The fixingunit of the printer unit 130 applies heat and pressure to the sheet tofix the visible image to the sheet.

The sheet accommodation unit 140 accommodates the sheet used for formingthe image in the printer unit 130. The sheet accommodation unit 140conveys the sheet to the printer unit 130. The sheet accommodation unit140 configures a sheet supply device (paper feed device) 1 according tothe embodiment.

The image reading unit 200 reads image information of a reading targetbased on brightness and darkness of light. The image reading unit 200records the read image information. The recorded image information maybe transmitted to another information processing apparatus via anetwork. Based on the recorded image information, the printer unit 130may form an image on the sheet.

As illustrated in FIG. 2, the sheet supply device 1 includes a tray 2(sheet stacking unit), a pickup roller (first roller) 3, a paper feedroller (second roller) 4, a separation roller (third roller) 5, twostoppers 6, and a pressing plate 7 (refer to FIG. 3).

For example, the tray 2 is formed in a rectangular flat shape. Asillustrated in FIG. 3, in the tray 2, a sheet bundle SS in which aplurality of sheets S are stacked can be stacked. An upper surface ofthe tray 2 is a stack surface 2 a on which the sheet bundle SS isstacked. For example, the stack surface 2 a is a horizontal surface.

As a local coordinate system of the tray 2, an XYZ orthogonal coordinatesystem is adopted. An X direction (first direction) is a supplydirection of the sheet S parallel to the stack surface 2 a of the tray2. A −X direction is a downstream side of the supply direction of thesheet S. The −X direction is a conveying direction of the sheet. The −Xdirection will also be simply referred to as “downstream side”. A Ydirection (second direction) is a direction parallel to the stacksurface 2 a and perpendicular to the X direction. The Y direction is awidth direction of the sheet S. A Z direction is a directionperpendicular to the stack surface 2 a of the tray 2. A +Z direction isa direction in which the sheet S is stacked on the stack surface 2 a.The +Z direction is a height direction. A position in the Z direction isa height position.

The pickup roller 3 is a driving roller. The pickup roller 3 has arotation shaft (not illustrated) parallel to the Y direction. The pickuproller 3 can come into contact with an uppermost sheet SA in the sheetbundle SS (hereinafter, also referred to as “uppermost sheet SA”)stacked on the tray 2. The pickup roller 3 conveys the sheets S in thesheet bundle SS stacked on the tray 2 to the downstream side one by onein order from the uppermost sheet SA.

The pickup roller 3 is positioned in the +Z direction with respect tothe tray 2. The pickup roller 3 can move close to and away from the tray2.

As illustrated in FIG. 2, the pickup roller 3 is present at a positionclose to an end portion 2 b of the tray 2 in the −X direction when seenfrom a direction parallel to the Z direction. The length of the pickuproller 3 in the Y direction is shorter than the dimension of the tray 2in the Y direction. The position of the pickup roller 3 in the Ydirection is a position corresponding to the center portion of the tray2 in the Y direction.

The paper feed roller 4 and the separation roller 5 are disposed outsideof the tray 2 in the −X direction when seen from the direction parallelto the Z direction. The paper feed roller 4 and the separation roller 5have a rotation shaft (not illustrated) parallel to the Y direction. Thepaper feed roller 4 is a driving roller and conveys the sheet S at thesame speed as that of the pickup roller 3. The lengths of the paper feedroller 4 and the separation roller 5 in the Y direction are shorter thanthe dimension of the tray 2 in the Y direction. The positions of thepaper feed roller 4 and the separation roller 5 in the Y direction arepositions corresponding to the center portion of the tray 2 in the Ydirection.

As illustrated in FIG. 3, the separation roller 5 is positioned in the−Z direction with respect to the paper feed roller 4. The separationroller 5 is a driven roller that operates together with the paper feedroller 4.

The paper feed roller 4 and the separation roller 5 further convey thesheet S conveyed from the tray 2 with a nip interposed therebetween. Thenip is a portion where outer circumferential surfaces of a pair ofrollers come into contact with (are pressed against) each other.

As illustrated in FIG. 2, the stopper 6 is present at a position closeto the end portion 2 b of the tray 2 in the −X direction when seen fromthe direction parallel to the Z direction. Two stoppers 6 are providedat different positions in the Y direction. Among the two stoppers 6, afirst stopper 6A is present at a position in the +Y direction furtherthan the center portion in the Y direction. Therefore, the position ofthe first stopper 6A in the Y direction is positioned in the +Ydirection with respect to the rollers 3, 4, and 5 at the center portionin the Y direction. Among the two stoppers 6, a second stopper 6B ispresent at a position in the −Y direction further than the centerportion in the Y direction. Therefore, the position of the secondstopper 6B in the Y direction is positioned in the −Y direction withrespect to the rollers 3, 4, and 5.

The two stoppers 6 are provided at different positions in the Ydirection perpendicular to the conveying direction of the sheet S.Therefore, the sheet S can be stably positioned. The position of thefirst stopper 6A in the Y direction is a position in the +Y directionwith respect to the pickup roller 3, and the position of the secondstopper 6B in the Y direction among the two stoppers 6 is a position inthe −Y direction with respect to the pickup roller 3. Therefore, thesheet S can be stably positioned.

As illustrated in FIG. 3, the stopper 6 is formed in a plate shape. Asurface of the stopper 6 in the +X direction is an abutting surface 6 aagainst which an end (leading end) of the sheet S in the −X directionabuts. The stopper 6 restricts the movement of the sheet S in the −Xdirection.

The stopper 6 is rotatable around the rotation shaft 8 in a θ direction.

The rotation shaft 8 is disposed in the Y direction at an end portion (alower end portion in FIG. 3) of the stopper 6 in the −Z direction. The θdirection is a direction around the rotation shaft 8. A +θ direction isa clockwise direction in FIG. 3. A −θ direction is a counterclockwisedirection in FIG. 3.

The rotation shaft 8 is present at a position close to the end portion 2b of the tray 2 in the −X direction. The position (the height directionin FIG. 3) of a shaft center 8 a of the rotation shaft 8 in the Zdirection is the same as the direction of the stack surface 2 a in the Zdirection or is present at a position in the −Z direction with respectto the stack surface 2 a. Specifically, in FIG. 3, the shaft center 8 aof the rotation shaft 8 is present at a height position that is lowerthan or equal to that of the stack surface 2 a.

When the shaft center 8 a of the rotation shaft 8 is present at a heightposition that is lower than or equal to that of the stack surface 2 a,the stopper 6 allows an operation of moving from a first posture P1(refer to FIG. 3) to a second posture P2 (refer to FIG. 4).

The stopper 6 rotates around the rotation axis 8 in the θ direction suchthat the posture thereof can switch between the first posture P1 (referto FIG. 3) and the second posture P2 (refer to FIG. 4).

In the first posture P1, the abutting surface 6 a of the stopper 6 istilted toward the downstream side (−X direction) as the distance fromthe stack surface 2 a in the +Z direction increases. Specifically, theabutting surface 6 a is tilted upward in the −X direction. In the firstposture P1, a tilt angle of the abutting surface 6 a with respect to thestack surface 2 a will be referred to as “α1” (first angle). The tiltangle α1 of the abutting surface 6 a in the first posture P1 is morethan 90°. The tilt angle α1 is an obtuse angle. The tilt angle α1 is anangle between the abutting surface 6 a and the stack surface 2 a.

In the first posture P1, the stopper 6 restricts the movement of thesheet S in the −X direction.

As illustrated in FIG. 4, in the second posture P2, the abutting surface6 a of the stopper 6 is tilted toward the downstream side (−X direction)as the distance from the stack surface 2 a in the +Z directionincreases. Specifically, the abutting surface 6 a is tilted upward inthe −X direction. In the second posture P2, a tilt angle of the abuttingsurface 6 a with respect to the stack surface 2 a will be referred to as“α2” (second angle). The tilt angle α2 of the abutting surface 6 a inthe second posture P2 is more than the tilt angle α1 of the abuttingsurface 6 a in the first posture P1. The tilt angle α2 of the abuttingsurface 6 a is more than 90°. The tilt angle α2 is an obtuse angle. Thetilt angle α2 is an angle between the abutting surface 6 a and the stacksurface 2 a.

For example, the stopper 6 can freely adjust the tilt angles α1 and α2of the abutting surface 6 a in the first posture P1 and the secondposture P2. In a case where the tilt angles α1 and α2 can be adjusted,for example, when multiple sheet feeding is likely to occur, the tiltangle α2 is reduced to suppress multiple sheet feeding. In addition,when the conveyance of the sheet S is likely to be congested, the tiltangle α2 is increased such that the conveyance of the sheet S can besmoothly performed. By adjusting the tilt angle α1, the adhesion forcebetween the sheets S can be adjusted.

It is desirable that the tilt angle of the stopper 6 can be adjusted bythe operation of the user in the control panel 120 (refer to FIG. 1).

The sheet supply device 1 includes a stopper driving unit such as amotor (not illustrated). The stopper driving unit rotates the stopper 6around the rotation shaft 8 in the θ direction. For example, asillustrated in FIGS. 3 and 4, the stopper driving unit rotates thestopper 6 in the −θ direction (the counterclockwise direction in FIGS. 3and 4) such that the stopper 6 can rotate from the first posture P1 tothe second posture P2.

As illustrated in FIG. 3, the pressing plate 7 has a pressing surface 7a configured to press an end (trailing end; an end opposite to theleading end) of the sheet bundle SS in the +X direction on the tray 2 inthe −X direction. The pressing surface 7 a is a tilted surface that istilted toward the downstream side (−X direction) as the distance fromthe stack surface 2 a in the +Z direction increases. The pressing plate7 has a dimension in the Y direction such that an end surface SSr(trailing end surface SSr) of the sheet bundle SS in the +X directioncan be pressed over the entire region in the height direction. The tiltangle of the pressing surface 7 a with respect to a reference surface 2c as an extended surface of the stack surface 2 a in the +X directionwill be referred to as “β”. The tilt angle β of the pressing surface 7 ais more than 90°. It is preferable that the pressing surface 7 a istilted in the same direction as that of the abutting surface 6 a in thefirst posture P1. It is desirable that the tilt angle β of the pressingsurface 7 a is equal to the tilt angle α1 of the abutting surface 6 a inthe first posture P1. When the tilt angle β of the pressing surface 7 ais equal to the tilt angle α1, the end surface of the sheet bundle SScan be accurately tilted at a predetermined angle.

In FIGS. 4 and 5, the pressing plate 7 is not illustrated.

The pressing plate 7 can be slid in the X direction. By moving thepressing plate 7 in the −X direction, the trailing end surface SSr ofthe sheet bundle SS can be pressed in the −X direction with the pressingsurface 7 a.

The sheet supply device can also adopt a configuration in which thepressing plate is not provided. In this case, it is preferable that,after stacking the sheet bundle SS on the stack surface 2 a, the sheetbundle SS is pressed using a different unit from the pressing plate toenter a state where the end surface is tilted (refer to FIG. 3). Forexample, the end surface can also be tilted as described above by theuser pressing the trailing end surface of the sheet bundle SS in the −Xdirection.

The control unit 150 (refer to FIG. 1) can control the posture of thestopper 6. For example, the control unit 150 can cause the stopperdriving unit to change the posture of the stopper 6 from the firstposture P1 to the second posture P2 along with the start of driving ofthe pickup roller 3 based on a signal for starting the driving of thepickup roller 3. A timing at which the posture of the stopper 6 changesfrom the first posture P1 to the second posture P2 may be at or afterthe start of driving of the pickup roller 3.

The control unit 150 can also cause the stopper 6 to change the posturefrom the first posture P1 to the second posture P2 along with the startof driving of the paper feed roller 4 based on a signal for starting thedriving of the paper feed roller 4. The control unit 150 can also causethe stopper driving unit to change the posture of the stopper 6 from thesecond posture P2 to the first posture P1.

Next, the operation of the sheet supply device 1 will be described.

In FIG. 3, the stopper 6 is in the first posture P1. The sheet bundle SSis stacked on the stack surface 2 a of the tray 2. At this time, theleading end surface and the trailing end surface of the sheet bundle SSare perpendicular to the stack surface 2 a.

By moving the pressing plate 7 in the −X direction, the trailing endsurface SSr of the sheet bundle SS can be pressed in the −X directionwith the pressing surface 7 a. Due to the pressing operation, an endsurface SSf (leading end surface SSf) of the sheet bundle SS in the −Xdirection is pressed against the abutting surface 6 a of the stopper 6in the first posture P1. The leading end surface SSf of the sheet bundleSS is a tilted surface along the abutting surface 6 a. The trailing endsurface SSr of the sheet bundle SS is a tilted surface along thepressing surface 7 a. The leading end surface SSf and the trailing endsurface SSr are tilted surfaces such that the relative position of thesheets S forming the sheet bundle SS changes in the X direction.Therefore, the adhesion force between the sheets S decreases.

By bringing the pickup roller 3 into contact with the uppermost sheet SAin the sheet bundle SS, the driving of the pickup roller 3 starts.

As illustrated in FIG. 4, the control unit 150 (refer to FIG. 1) causesthe stopper driving unit to change the posture of the stopper 6 from thefirst posture P1 to the second posture P2 along with the start ofdriving of the pickup roller 3.

The pickup roller 3 conveys the sheets S in the sheet bundle SS to thedownstream side one by one in order from the uppermost sheet SA. Theuppermost sheet SA abuts against the abutting surface 6 a of the stopper6 and is guided to a gap between the paper feed roller 4 and theseparation roller 5 along the tilt of the abutting surface 6 a.

The pickup roller 3 may be conveyed in a state where two or more sheetsS overlap each other. The conveyed sheets S abut against the abuttingsurface 6 a of the stopper 6. Since the tilt angle α2 of the abuttingsurface 6 a in the second posture P2 is large, the uppermost sheet SAslides and travels on the abutting surface 6 a and is guided to the gapbetween the paper feed roller 4 and the separation roller 5. On theother hand, the sheets S other than the uppermost sheet SA are stoppedat the abutting surface 6 a. Therefore, only the uppermost sheet SA isguided to the gap between the paper feed roller 4 and the separationroller 5.

When two or more overlapping sheets S are guided to the gap between thepaper feed roller 4 and the separation roller 5, only the uppermostsheet SA is separated as follows. As described above, the adhesion forcebetween the sheets S is decreased. Therefore, the coefficient offriction between the sheet S on the upper layer (upper-layer sheet) andthe other sheets S (lower-layer sheets) is lower than the coefficient offriction between the paper feed roller 4 and the separation roller 5,and the sheet S. Therefore, when a conveying force is applied from thepaper feed roller 4 to the upper-layer sheet, only the upper-layer sheet(the uppermost sheet SA) is conveyed, and the lower-layer sheets arestopped with the separation roller 5.

The paper feed roller 4 and the separation roller 5 further convey thesheet S with a nip interposed therebetween. The sheet S is conveyed tothe printer unit 130 through a conveying device (conveying unit; notillustrated) including a guide 9.

The sheet supply device 1 and the image forming apparatus 100 includethe stopper 6 that is freely rotatable. The stopper 6 can switch theposture between the first posture P1 and the second posture P2 having atilt angle more than that in the first posture P1. Therefore, the sheetsS can be conveyed one by one in a state where the posture of the stopper6 is changed from the first posture P1 to the second posture P2 aftertilting the end surface of the sheet bundle SS with the stopper 6 in thefirst posture P1.

When two or more sheets S are conveyed in a state where the sheetsoverlap each other, the sheets S come into contact with the abuttingsurface 6 a. However, only the uppermost sheet SA slides and travels onthe abutting surface 6 a having a large tilt angle and is guided to thegap between the paper feed roller 4 and the separation roller 5.Accordingly, multiple sheet feeding of the sheets S can be suppressed.

In order to clarify the effects of the sheet supply device 1 accordingto the embodiment, a sheet supply device according to a comparativeembodiment will be described as an example. The components common tothose of the sheet supply device 1 according to the embodimentillustrated in FIGS. 2 to 5 are represented by the same referencenumerals, and the description thereof will not be repeated.

As illustrated in FIGS. 6 and 7, a sheet supply device 101 according toa comparative embodiment includes a tray 102, the pickup roller 3, thepaper feed roller 4, the separation roller 5, and a stopper 106. Asillustrated in FIG. 7, the stopper 106 includes a main portion 106 aperpendicular to a stack surface 102 a and a tilted portion 106 b. Thetilted portion 106 b is tilted upward to the downstream side (−Xdirection) from an upper end of the main portion 106 a.

The sheet bundle SS is stacked on the stack surface 102 a of the tray102. The end surface of the sheet bundle SS is perpendicular to thestack surface 102 a.

As illustrated in FIGS. 8 and 9, the tray 102 is lifted such that theuppermost sheet SA is conveyed to the downstream side by the pickuproller 3. When two or more sheets S are conveyed in a state where thesheets S overlap each other, the sheets S may be guided to the gapbetween the paper feed roller 4 and the separation roller 5.

FIGS. 10 and 11 are schematic diagrams illustrating modificationexamples of the stopper 6.

As illustrated in FIGS. 10 and 11, a surface material 16 may bedetachably attached to the abutting surface 6 a of the stopper 6. Asurface 16 a of the surface material 16 has a coefficient of staticfriction different from a coefficient of static friction of the abuttingsurface 6 a. The surface 16 a functions as a new abutting surface 16 a.

With this configuration, the coefficient of static friction of thesurface (the abutting surface) of the stopper 6 can be set depending onthe characteristics of the sheet S (the adhesion force between thesheets, the rigidity of the sheet, and the like). Accordingly, multiplesheet feeding can be suppressed, and smooth conveyance can be realized.

A method of adjusting the coefficient of static friction of the abuttingsurface 6 a of the stopper 6 is not limited to the attachment of thesurface material 16. For example, an adjusting member having acoefficient of static friction different from that of the abuttingsurface may be inserted into a hole portion formed in the stopper.

As illustrated in FIG. 2, in the sheet supply device 1, the number ofthe stoppers 6 is two. However, the number of stoppers is notparticularly limited. For example, the number of the stoppers may be 1or any number of 2 or more.

In at least one of the embodiments described above, the stopper 6rotates such that the posture can switch between the first posture P1and the second posture P2. Accordingly, in the sheet supply device 1,multiple sheet feeding of the sheets S can be suppressed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A sheet supply device, comprising: a sheetstacking component having a stack surface on which a plurality of sheetsare stacked; a first roller configured to convey an uppermost sheet ofthe plurality of sheets from the sheet stacking component toward adownstream side in a conveying direction of the sheet; a second rollerconfigured to further convey the sheet conveyed by the first roller; anda stopper rotatable around a rotation shaft along a width direction ofthe sheet parallel to the stack surface and perpendicular to theconveying direction, the stopper having an abutting surface againstwhich a leading end of the sheet on the downstream side in the conveyingdirection abuts, wherein the stopper rotates around the rotation shaftsuch that a posture of the stopper switches between a first posturehaving a first angle at which an angle between the abutting surface andthe stack surface is an obtuse angle, and a second posture having asecond angle at which an angle between the abutting surface and thestack surface is an obtuse angle, the second angle being greater thanthe first angle.
 2. The sheet supply device according to claim 1,wherein a shaft center of the rotation shaft is present at a heightposition that is lower than or equal to a height position of the stacksurface.
 3. The sheet supply device according to claim 1, wherein thestopper is configured to freely adjust the angles of the abuttingsurface in the first posture and the second posture.
 4. The sheet supplydevice according to claim 1, further comprising: a pressing plateconfigured to press a trailing end of the sheet stacked on the stacksurface opposite to the leading end such that the leading end is pressedagainst the abutting surface.
 5. The sheet supply device according toclaim 4, wherein the pressing plate has a pressing surface configured topress the trailing end of the sheet, and a tilt angle of the pressingsurface with respect to the stack surface is equal to a tilt angle ofthe abutting surface when the stopper is in the first posture.
 6. Thesheet supply device according to claim 1, wherein a plurality ofstoppers are provided, and the stoppers are provided at differentpositions in the width direction of the sheet.
 7. The sheet supplydevice according to claim 1, wherein a surface material having acoefficient of static friction different from a coefficient of staticfriction of the abutting surface is attachable to the stopper.
 8. Thesheet supply device according to claim 1, wherein the first roller, thesecond roller, and stopper are configured to convey a single sheet inthe conveying direction, with the proviso that two or more sheets arenot conveyed at one time by the first roller, the second roller, andstopper.
 9. An image forming apparatus, comprising: a sheet supplydevice, comprising: a sheet stacking component having a stack surface onwhich a plurality of sheets are stacked; a first roller configured toconvey an uppermost sheet of the plurality of sheets from the sheetstacking component toward a downstream side in a conveying direction ofthe sheet; a second roller configured to further convey the sheetconveyed by the first roller; and a stopper rotatable around a rotationshaft along a width direction of the sheet parallel to the stack surfaceand perpendicular to the conveying direction, the stopper having anabutting surface against which a leading end of the sheet on thedownstream side in the conveying direction abuts, wherein the stopperrotates around the rotation shaft such that a posture of the stopperswitches between a first posture having a first angle at which an anglebetween the abutting surface and the stack surface is an obtuse angle,and a second posture having a second angle at which an angle between theabutting surface and the stack surface is an obtuse angle, the secondangle being greater than the first angle; and an image forming deviceconfigured to form an image on a sheet conveyed by the sheet supplydevice.
 10. The image forming apparatus according to claim 9, furthercomprising a controller configured to control a posture of the stopper.11. The image forming apparatus according to claim 10, wherein thecontroller causes the stopper to rotate from the first posture to thesecond posture along with the start of driving of the first roller. 12.The image forming apparatus according to claim 9, wherein a shaft centerof the rotation shaft is present at a height position that is lower thanor equal to a height position of the stack surface.
 13. The imageforming apparatus according to claim 9, wherein the stopper isconfigured to freely adjust the angles of the abutting surface in thefirst posture and the second posture.
 14. The image forming apparatusaccording to claim 9, further comprising: a pressing plate configured topress a trailing end of the sheet stacked on the stack surface oppositeto the leading end such that the leading end is pressed against theabutting surface.
 15. The image forming apparatus according to claim 14,wherein the pressing plate has a pressing surface configured to pressthe trailing end of the sheet, and a tilt angle of the pressing surfacewith respect to the stack surface is equal to a tilt angle of theabutting surface when the stopper is in the first posture.
 16. The imageforming apparatus according to claim 9, wherein a plurality of stoppersare provided, and the stoppers are provided at different positions inthe width direction of the sheet.
 17. The image forming apparatusaccording to claim 9, wherein a surface material having a coefficient ofstatic friction different from a coefficient of static friction of theabutting surface is attachable to the stopper.
 18. The image formingapparatus according to claim 9, wherein the first roller, the secondroller, and stopper are configured to convey a single sheet in theconveying direction, with the proviso that two or more sheets are notconveyed at one time by the first roller, the second roller, andstopper.
 19. A sheet supply method, comprising: conveying by a firstroller an uppermost sheet of a plurality of sheets from a sheet stackingcomponent having a stack surface on which the plurality of sheets arestacked toward a downstream side in a conveying direction of the sheet;conveying by a second roller the sheet conveyed by the first roller; androtating a stopper around a rotation shaft along a width direction ofthe sheet parallel to the stack surface and perpendicular to theconveying direction, the stopper having an abutting surface againstwhich a leading end of the sheet on the downstream side in the conveyingdirection abuts, and switching a posture of the stopper between a firstposture having a first angle at which an angle between the abuttingsurface and the stack surface is an obtuse angle, and a second posturehaving a second angle at which an angle between the abutting surface andthe stack surface is an obtuse angle, the second angle being greaterthan the first angle.
 20. The sheet supply method according to claim 19,further comprising: pressing a trailing end of the sheet stacked on thestack surface opposite to the leading end such that the leading end ispressed against the abutting surface.